Hydrogenation of unsaturated hydrocarbons employing a metal sulfide catalyst having a nitrogenous base chemisorbed thereon



United States Patent Archibald P. Stuart, Media, Pa., assignor to SunOil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing.Application January 27, 1951,

Serial No. 208,232

17 Claims. (Cl. 196-78) This invention relates to new catalyticcompositions. More particularly, the invention relates to newhydrogenation catalysts and to processes for their use.

Various metallic sulfides, either alone or deposited on a carrier, haveheretofore been employed in hydrogenation reactions. The carriersheretofore successfully employed in hydrogenation processes are, ingeneral, those which exhibit substantially no acidic properties, such astitania, alumina, and magnesia, and such carriers generally containsilica, if at all, in only minor and incidental quantities or combinedin an inactive form. The choice of carriers for hydrogenation reactionshas thus been rather limited. Activators for such catalysts such asmetallic oxides, halides, and the like, have been described. Suchcatalysts and catalytic compositions, however, are usually subject toone or more difficulties which prevent their use in commercialoperations. For example, such catalysts are expensive to prepare, or arenot sufiiciently effective to cause hydrogenation of difficultyhydrogenatable hydrocarbons, such as aromatics, without the use ofrelatively drastic conditions, and the use of such drastic conditionscauses undesired reactions, such as cracking. Also, heretofore describedcatalysts are often rapidly deactivated in the hydrogenation reactions,and regeneration is difficult and expensive.

An object of the present invention is to produce a highly effectiveinexpensive hydrogenation catalyst. A further object is to provide acatalyst which may be employed for long periods of timewithoutdeactivation. Another object is to provide a catalyst effectivein hydrogenation reactions wherein only relatively mild conditions arerequired. A further object is to provide an effective hydrogenationcatalyst including a siliceous material as the carrier. A still furtherobject is to provide a process for the use of the present novelcatalyst.

It has now been found that by incorporating a small amount of anitrogen-containing organic base on a hydrogenation catalyst comprisinga metal sulfide deposited on a carrier produces a catalytic compositionremarkably effective in hydrogenation processes. It has been furtherfound that this catalytic composition is inexpensive, has a long life,and is effective for the hydrogenation of unsaturated hydrocarbons underrelatively mild conditions.

In accordance with the present invention, a metallic sulfide isdeposited on a carrier and the resulting composition treated with anorganic nitrogenous base. The effective quantity of the base is thatamount which is chemisorbed by the catalyst, and the so-formedcomposition is the catalyst of the present invention.

By the expression chemisorbed, and terms of similar import, as usedherein, is meant that quantity of nitrogenous base adsorbed on thecatalyst which is held by bonds stronger than mere physical adsorption.Thus, physically adsorbed base may be relatively readily removed bydesorption, whereas the chemisorbed base can be removed only by resortto relatively drastic conditions. For example, the portion of organicbase held by physical 2,736,689 Patented Feb. 28, 1956;

adsorption is readily removed by maintaining the composition at atemperature above the boiling point and below the decomposition point ofthe base in a stream of an inert gas for time sufficient to achievedesorption, from about 1 to 6 hours usually being sufficient. Thechemisorbed portion of the organic base is not affected by thisoperation.

The metal sulfides which may be employed as the hydrogenation catalystsare the sulfides of the metals of groups 2 through 8 of the periodictable, and preferably of the metals of group 6 or 8. Preferred metalsulfides are the sulfides of iron, cobalt, nickel, molybdenum, chromium,tungsten, and vanadium. These metal sulfides may be deposited oncarriers heretofore employed including, for example, bauxite, alumina,silica gel, mixtures of alumina and silica gel including physicalmixtures and coprecipitated compositions, and the like. The presentinvention has been found to be especially valuable where an acid typecarrier is used, and preferably where the carrier is a siliceouscarrier, i. e., a carrier having silica as a component thereof. Thus,while the invention may be employed with carriers heretofore used, it isof special value with siliceous or acid type carriers heretoforeconsidered undesirable for use in hydrogenation processes. A preferredembodiment of the present invention comprises using as the carrier aspent cracking catalyst. In patent application Serial No. 200,700, filedDecember 13, 1950, now Patent No. 2,635,081, there is described andclaimed a catalytic composition comprising molybdenum disulfidedeposited on a spent cracking catalyst, and the further treatment ofthis composition with an organic nitrogenous base in accordance with thepresent invention constitutes a preferred embodiment thereof. Asdescribed in said patent application Serial No. 200,700, the spentcracking catalyst is preferably a catalyst consisting of silica andalumina which has been employed for the catalytic cracking ofhydrocarbons until the cracking activity in the cracking operation hasdecreased at least about 30% below its initial value, so thatregeneration for further use in cracking is not feasible. Silicaaluminacracking catalysts are well known, and generally contain a ratio ofsilica to alumina of 1:1 to 15:1 and preferably from 70% to silica, from30% to 10% alumina, and not more than 10% of other metallic oxides.

The organic nitrogenous bases which may be employed are the organicnitrogenecontaining compounds having a basic reaction, or anitrogen-containing compound which is converted thereto under theconditions of the hydrogenation processes such as butyl cyanide andcyclohexanone oxime. It is preferred to employ an organic base wherein anitrogen atom is connected in a ring which may be of aromatic oraliphatic character. Examples of preferred organic bases are quinoline,pyridine, quinaldine, piperidine, and pyrrole. Other organic nitrogenousbases which may be employed with good results include, for example,aniline, toluidine, decylamine, and other amines. The nitrogen baseshould not be decomposed under the conditions of hydrogenation and hencebases wherein the nitrogen atom is connected to a tertiary carbon atomare not preferred. Preferred nitrogenous bases are. those wherein thenitrogen atom is connected to a primary or secondary carbon atom oratoms, and which have from 4 to 16 carbon atoms per molecule.

The present catalyst is prepared by first depositing a metallic sulfideon a carrier which may be accomplished as heretofore known. For example,molybdenum disulfide is deposited on a carrier such as bauxite or aspent cracking catalyst by impregnating the carrier with an aqueoussolution of ammonium molybdate, treating the impregnated carrier withhydrogen sulfide and heating the so-treated composition in an atmosphereof hydrogen. In accordance with the present invention, this compositionshould contain from to by weight of the metal sulfide. The so-preparedcomposition is then treated with an organic nitrogenous base. This maybe conveniently accomplished by passing a stream of an inert gas admixedwith vapors of the organic base over the catalyst at an elevatedtemperature, preferably from 100 C. to 500 C. The physically adsorbedbase may then be removed by continuing the contact, at an elevatedtemperature, with the stream of inert gas without the added vapors ofthe base. This causes desorption of the physically adsorbed base leavingthe chemisorbcd base attached to the catalytic composition. Othermethods may be employed, such as dipping the catalyst in the liquid orliquefied base, or in a solution thereof, and thereafter heatingpreferably in a vacuum or in a stream of inert gas to desorb thephysically adsorbed base. Only a relatively small amount of organic baseis chemisorbed and such small amount results in a large increase inhydrogenation eflicicacy. The amount of chemisorbed base will varysomewhat to the carrier employed, but will usually be between 0.01 and0.2 milliequivalent per gram of metal sulfide-carrier. With preferrednitrogenous bases having from 4 to 16 carbon atoms per molecule, thequantity of chemisorbed base corresponding to these milliequivalentvalues will be from 0.065 to 4.5% by weight of the final composition.All of the physically adsorbed base need not be removed since a smallamount thereof does not cause deleterious effects in the hydrogenationprocess. Excessive amounts of physically adsorbed base tend to beremoved or desorbed from the composition during hydrogenation and maycontaminate the product.

In accordance with the present invention, it is essential that thecatalyst be treated with the nitrogenous base prior to its use inhydrogenation processes, i. e., the addition of a nitrogenous base to anoil and subsequent hydrogenation thereof does not give comparableresults, and may exhibit deleterious effects as shown in the followingexamples.

The catalysts of the present invention are especially suitable for thehydrogenation of the aromatic constituents of petroleum fractions. Forexample, the properties of lubricating oil containing aromatichydrocarbons may be improved by hydrogenating in accordance with thepresent invention. It is especially advantageous to hydrogenate one-passgas oil to improve the crackability thereof. For example, hydrogenationof a one-pass gas oil having a boiling point of from about 400 to 700 F.and

containing from to 50% aromatic hydrocarbons,

principally polynuclear aromatics such as naphthalenes, to convert aportion thereof to tetralins and decalins, and subsequent crackingresults in an increase in the gasoline yield and a decrease in cokeformation. Other unsaturated hydrocarbons, such as olefins andacetylenes, and hydrocarbon mixtures containing such unsaturatedhydrocarbons, may advantageously be hydrogenated in the pres ence of thepresent catalyst.

The catalysts of the present invention are etfective for thehydrogenation of aromatic hydrocarbons, such as naphthalenes, underrelatively mild conditions, the optimum conditions for a givenapplication being dependent upon the charge stock, the degree ofhydrogenation desired, and the like. In general, using the presentcatalysts, hydrogenation is advantageously obtained by using a hydrogenpressure of from 500 to 1,800 p. s. i., and preferably from 1,000 to1,600 p. s. i., and a temperature of from 200 C. to 400 C., andpreferably from 250 C. to 360 C. Higher temperatures and pressures canbe used, so long as the operating variables are maintained withinhydrogenating conditions.

The following examples illustrate preferred embodiments of the presentinvention which is not necessarily to be considered as limited thereby.

Example 1 In order to demonstrate the effectiveness of the presentcatalyst and the process of the present invention, a spentsilica-alumina cracking catalyst was coated with 21.4% molybdenumdisulfide. The spent cracking catalyst consisted of about 75% silica andabout 25% alumina and had been employed for about 6 months in acommercial installation involving the catalytic cracking of a gas oil.During the period of cracking, the catalyst had been subjected to about10,000 regenerations and the initial activity of decreased so thatregeneration restored an activity of 29, i. e. the catalytic activitydecreased by 35.6%. Catalytic activity was measured by the methoddescribed by Alexander, Proceedings Am. Pet. Inst. 27 (III) 51 (Nov.1947). An analysis of the spent catalyst showed the presence of minoramounts of various metals including at least about 0.1% to 1% oftitanium, vanadium, and iron, and at least about 0.001% to 0.1%chromium, and at least about 0.01% to 1% nickel. This spent catalyst wasimpregnated with an aqueous solution of ammonium molybdate. Water wasexpelled by gentle heating, the resulting mass treated with hydrogensulfide to convert the ammonium compounds to ammonium thiomolybdatc. Thecomposition was then heated to 300 C. in an atmosphere of hydrogen toconvert the thiomolybdate to the disulfide. The final compositioncontained 21.4% molybdenum disulfide.

A portion of the so-prepared catalyst was treated with vapors ofquinoline at 300 C. in a stream of nitrogen. This was accomplished bythe dropwise addition of quinoline to the heated catalyst maintained ina stream of nitrogen. Excess quinoline, i. e. the quinoline notchemisorbed, was removed by passing a stream of nitrogen over thecatalyst, at 300 C., for 4 hours.

Both of the catalysts were used to hydrogenate onepass catalytic gas oilhaving a refractive index :1 =1.4940, a density d4 =0.8723 andcontaining by weight saturates, 32% naphthalenes, and 3% tetralins andboiling between 439 F. and 654 F. in saturating aromatic bonds, e. g. inhydrogenating naphthalene to tetralin and decaiin, the refractive indexof the hydrocarbon mixture is decreased and this decrease in refractiveindex constitutes a measure of the degree of: hydrogenation. Operatingconditions were 1,500 p. s. i. at a temperature of 340 C. and a spacerate (liquid hourly space velocity) of l. A decrease in the refractiveindex (n 10 of 131 was observed for the catalyst not treated withquinoline, whereas a decrease of 200 was observed for the quinolinetreated catalyst. This indicates a substantial amount of hydrogenationwherein naphthalenes were converted to tetralins. The product obtainedwith the catalyst not treated with quinoline contained about twice theconcentration of unconverted naphthalenes as did the product obtainedfrom the process using the quinoline treated catalyst.

Thus, while molybdenum sulfide deposited on a spent cracking catalystserves as a good hydrogenation catalyst, treatment thereof Withquinoline in accordance with the present invention produces a markedlysuperior catalyst.

Example 2 Example 1 was duplicated using bauxite as the carrier in placeof spent cracking catalyst. The refractive index (n 10 change withquinoline treated catalyst was 21 units greater than the change observedwith untreated catalyst.

Example 3 A catalyst consisting of 21.4% molybdenum sulfide deposited onalumina was prepared as described in Example 1. To the same catalyticgas oil of Example 1 was added 0.5 volume percent of quinoline and themixture was hydrogenated in contact with the above catalyst at atemperature of 340 C. and pressure of 1,500 p. s. i. The refractiveindex change with added quinoline was 45 X- units less than whenquinoline was not added, showing that hydrogenation was retarded by theso-added quinoline. This deleterious effect was not observed when thecatalyst was treated, prior to the hydrogenation process, so thatquinoline was chemisorbed thereon.

In the foregoing examples, which include runs of more than 24 hours, nodecrease in hydrogenating activity of the quinoline treated catalystswas observed.

The invention claimed is:

1. An improved hydrogenating catalytic composition prepared bydepositing on an acid type carrier from 10% to 25% of a metal sulfideselected from the group consisting of iron sulfide, cobalt sulfide,nickel sulfide, molybdenum sulfide, chromium sulfide, tungsten sulfide,and vanadium sulfide, and treating the resulting composition undernon-hydrogenating conditions with an organic nitrogenous base havingfrom 4 to 16 carbon atoms per molecule for a time sufiicient tochemisorb said base thereon in an amount efiective to increasehydrogenating activity of said resulting composition 2. An improvedhydrogenating catalytic composition according to claim 1 wherein saidorganic nitrogenous base is selected from the group consisting ofquinoline, pyridine, quinaldine, piperidine, and pyrrole.

3. An improved hydrogenating catalytic composition according to claim 1wherein said acid type carrier is a siliceous carrier.

4. An improved hydrogenating catalytic composition according to claim 1wherein said acid type carrier is a spent cracking catalyst.

5. An improved hydrogenating catalytic composition according to claim 1wherein said acid type carrier is bauxite.

6. An improved hydrogenating catalytic composition prepared bydepositing on a spent cracking catalyst from 10% to 25% molybdenumdisulfide and treating the resulting composition under non-hydrogenatingconditions with an organic nitrogenous base having from 4 to 16 carbonatoms per molecule for a time sufficient to chemisorb from 0.065 to 4.5%of said base thereon, said spent cracking catalyst comprising asilica-alumina composition previously utilized as the catalyst in aprocess for cracking hydrocarbons until its cracking activity in thecracking operation had decreased at least 30% below its initialactivity.

7. An improved hydrogenating catalytic composition according to claim 6wherein said organic nitrogenous base is quinoline.

8. An improved hydrogenating catalytic composition prepared bydepositing on bauxite from 10% to 25% molybdenum disulfide and treatingthe resulting composition under non-hydrogenating conditions With anorganic nitrogenous base having from 4 to 16 carbon atoms per moleculefor a time sufiicient to chemisorb from 0.065 to 4.5% of said basethereon.

9. An improved hydrogenating catalytic composition according to claim 8wherein said organic nitrogenous base is quinoline.

10. Process for the hydrogenation of unsaturated hydrocarbons whichcomprises contacting said unsaturated hydrocarbons under hydrogenatingconditions with a catalytic composition prepared by depositing on anacid type carrier from 10% to 25% of a metal sulfide selected from thegroup consisting of iron sulfide, cobalt sulfide, nickel sulfide,molybdenum sulfide, chromium sulfide, tungsten sulfide, and vanadiumsulfide, and treating the resulting composition under non-hydrogenatingconditions with an organic nitrogenous base for a time suflicient tochemisorb thereon said base in an amount efiective to increasehydrogenating activity of said resulting composition.

11. Process according to claim 10 wherein said metal sulfide ismolybdenum sulfide.

12. Process according to claim 10 wherein said organic nitrogenous baseis quinoline.

13. Process for the hydrogenation of unsaturated hydrocarbons whichcomprises contacting said unsaturated hydrocarbons under hydrogenatingconditions with a composition prepared by depositing from 10% to 25%molybdenum sulfide on a spent cracking catalyst and treating theresulting composition under non-hydrogenating conditions with quinolinefor a time sufiicient to chemisorb thereon from 0.065 to 4.5 quinoline.

14. Process for the hydrogenation of unsaturated hydrocarbons whichcomprises contacting said unsaturated hydrocarbons under hydrogenatingconditions with a composition prepared by depositing from 10% to 25%molybdenum sulfide on bauxite and treating the resulting vcompositionwith quinoline for a time sufiicent to chemisorb thereon from 0.065 to4.5 quinoline.

15. Process for the preparation of an improved hydrogenating catalyticcomposition which comprises depositing a metal sulfide selected from thegroup consisting of iron sulfide, cobalt sulfide, nickel sulfide,molybdenum sulfide, chromium sulfide, tungsten sulfide, and vanadiumsulfide on an acid type carrier, and treating the resulting compositionunder non-hydrogenating conditions with an organic nitrogenous base invapor phase for a time sulficient to chemisorb said nitrogenous base inan amount efiective to increase the hydrogenating activity of saidresulting composition.

16. Process for the preparation of an improved hydrogenating catalyticcomposition which comprises depositing from 10% to 25% molybdenumsulfide on bauxite and treating the resulting composition undernon-hydrogenating conditions with quinoline in the vapor phase undernon-hydrogenating conditions for a time sufiicient to chemisorb from0.065 to 4.5 by weight quinoline.

17. Process for the preparation of an improved hydrogenating catalyticcomposition which comprises depositing from 10% to 25% molybdenumsulfide on a spent cracking catalyst and treating the resultingcomposition under non-hydrogenating conditions with quinoline in thevapor phase for a time sufficient to chemisorb from 0.065 to 4.5 byweight quinoline.

References Cited in the file of this patent UNITED STATES PATENTS2,332,276 Stahly Oct. 19, 1943 2,366,724 Gardner Jan. 9, 1945 2,429,575Appleby et a1. Oct. 21, 1947 2,550,531 Ciapetta Apr. 24, 1951

1. AN IMPROVED HYDROGENATING CATALYTIC COMPOSITION PREPARED BYDEPOSITING ON AN ACID TYPE CARRIER FROM 10% TO 25% OF A METAL SULFIDESELECTED FROM THE GROUP CONSISTING OF IRON SULFIDE, COBALT SULFIDE,NICKEL SULFIDE, MOLYBDENUM SULFIDE CHROMIUM SULFIDE, TUNGSTEN SULFIDE,AND VANADIUM SULFIDE, AND TREATING THE RESULTING COMPOSITION UNDERNON-HYDROGENATING CONDITIONS WITH AN ORGANIC NITROGENOUS BASE HAVINGFROM 4 TO 16 CARBON ATOMS PER MOLECULE FOR A TIME SUFFICIENT TOCHEMISORB SAID BASE THEREON IN AN AMOUNT EFFECTIVE TO INCREASEHYDROGENATING ACTIVITY OF SAID RESULTING COMPOSITION.